1. Technical Field
The disclosure relates to a hybrid vehicle and, more particularly, to charge and discharge control over a secondary battery mounted on a hybrid vehicle while the hybrid vehicle is traveling.
2. Description of Related Art
A hybrid vehicle is able to charge a vehicle-mounted secondary battery by the use of power generation that accompanies engine operation even during traveling. For this reason, as described in Japanese Patent Application Publication No. 2011-225079 (JP 2011-225079 A), charging and discharging of a secondary battery are controlled by executing forcible discharge control or forcible charge control such that the state of charge (SOC) of the secondary battery is kept within a predetermined range. Particularly, JP 2011-225079 A describes control for changing a control center SOC in response to the number of times forcible charge control is executed and the number of times forcible discharge control is executed.
Japanese Patent Application Publication No. 2003-047108 (JP 2003-047108 A) describes that, when the charge memory effect of a secondary battery has been detected, the memory effect is eliminated while a decrease in vehicle performance and battery degradation are avoided by increasing a target SOC.
However, in the control described in JP 2011-225079 A, ordinary charge and discharge control is executed before forcible charging caused by an approach of the SOC to a control lower limit is actually performed a certain number of times. For this reason, it is not possible to sufficiently avoid occurrence of the memory effect, so there is a concern that charge and discharge control over the secondary battery is changed after the memory effect has occurred as in the case of JP 2003-047108 A.